Audio devices, such as mobile phones, multimedia players, Personal Digital Assistants, game consoles or other types of audio devices, are known in the art. Such devices typically include one or more amplifier circuits which are able to amplify different types of audio signals for different audio amplification functions. For example, for mobile phones, the main audio amplification functions are for the following use cases:
emitting a ring tone to alert the user of an incoming call by means of a loudspeaker or allowing hands free operation through a loudspeaker;
allowing the user to hear through a dedicated earpiece during a voice call;
hearing a conversation or music through a headset;
sending a music signal to an external unit through a line out path.
For each acoustic transducer used by the audio amplification function, a separate power amplifier is present which drives the corresponding signal to the respective transducer.
Thus, in case of three audio amplification functions, of which two require a stereo output and hence use two transducers each, a total of five power amplifiers is required, even if not all the functions are active at the same time. This consumes a significant amount of die space in case the amplifier circuit is implemented as a semiconductor device and/or results in a relatively high power consumption.